|Turbulent convection and high‐frequency internal wave details in 1‐m shallow waters
In: Limnology and Oceanography. American Society of Limnology and Oceanography: Waco, Tex., etc. ISSN 0024-3590; e-ISSN 1939-5590, meer
Vertically 0.042‐m‐spaced moored high‐resolution temperature sensors are used for detailed internal wave‐turbulence monitoring near Texel North Sea and Wadden Sea beaches on calm summer days. In the maximum 2‐m deep waters, irregular internal waves are observed supported by the density stratification during day‐times’ warming in early summer, outside the breaking zone of < 0.2 m surface wind waves. Internal‐wave–induced convective overturning near the surface and shear‐driven turbulence near the bottom are observed in addition to near‐bottom convective overturning due to heating from below. Small turbulent overturns have durations of 5–20 s, close to the surface wave period and about one third to one tenth of the shortest internal wave period. The largest turbulence dissipation rates are estimated to be of the same order of magnitude as found above deep‐ocean seamounts, whereas overturning scales are observed 100 times smaller. The turbulence inertial subrange is observed to link between the internal and surface wave spectral bands.